In my experience those one type of bug are also the hardest bugs to find and fix, even when you know it's sometimes happening. The system can get sufficiently c

In my experience those one type of bug are also the hardest bugs to find and fix, even when you know it's sometimes happening. The system can get sufficiently complex such that it's near impossible to find the bug unless you get lucky. And often when you find the bug it can result in an apparently architectural contradiction and it becomes very non-obvious how to fix it as there are two architectural decisions that happen to be at odds with each other rather than a simple mistake.